MobiCacher: Mobility-aware content caching in small-cell networks

Small-cell networks have been proposed to meet the demand of ever growing mobile data traffic. One of the prominent challenges faced by small-cell networks is the lack of sufficient backhaul capacity to connect small-cell base stations (small-BSs) to the core network. We exploit the effective application layer semantics of both spatial and temporal locality to reduce the backhaul traffic. Specifically, we envision that small-BSs are equipped with storage facility to cache contents requested by users. As the cache hit ratio increases, most of the users´ requests can be satisfied locally without incurring traffic over the backhaul. To make informed caching decisions, the mobility patterns of users must be carefully considered as users might frequently migrate from one small cell to another. We study the issue of mobility-aware content caching, which is formulated into an optimization problem with the objective to maximize the caching utility. As the problem is NP-complete, we develop a polynomial-time heuristic solution termed MobiCacher with bounded approximation ratio. We conduct trace-based simulations to evaluate the performance of MobiCacher, which show that MobiCacher yields better caching utility than existing solutions.